Design method and system of polarization detection metasurface

Abstract

The application discloses a design method and system of a polarization detection metasurface. The method comprises the following steps: establishing a microstructure model, scanning the phase delay of microstructures with different geometric sizes under x and y polarizations; specifying two groups of orthogonal polarization states and target propagation angles, calculating the supercell size and the number of microstructures contained therein, and confirming the polarization beam splitting target required under the two groups of orthogonal polarization states; calculating the Jones matrix of each microstructure in the supercell and selecting a group of microstructure parameters as the initial solution; establishing a supercell model according to the initial solution and performing forward propagation simulation to obtain the diffraction order intensity distribution under the two groups of orthogonal polarizations, and constructing a loss function to obtain the optimal supercell structure meeting the polarization beam splitting target after iterative optimization; and performing two-dimensional periodic expansion on the supercell structure to obtain a metasurface structure. The application can realize efficient separation of multiple polarization states on a single metasurface, avoids the crosstalk problem in the traditional space division multiplexing mode, and improves the spatial resolution.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical metasurface, and particularly to a design method and system of a polarization detection metasurface. BACKGROUND

[0002] Polarization is an important physical property of light, and has wide applications in 3D imaging, stress analysis, biosensing, etc. Traditional polarization detection methods usually adopt a mechanical rotating polarizer, and collect light intensity information of different polarization states through time division multiplexing. This method has the disadvantages of large volume, slow response speed, poor detection ability for dynamic targets, etc.

[0003] In recent years, metasurfaces (Mie scattering, diffraction, etc.) as a two-dimensional artificial microstructure material, due to their flexible control ability of light field, provide a new technical path for integrated and real-time polarization detection. In the prior art, different polarization control functions of supercells are combined to realize multi-polarization state detection by using space division multiplexing. However, this method has the problems of high cross-talk and low spatial resolution, which limits its application in high-precision imaging and dynamic detection. metasurface

[0004] Therefore, it is necessary to propose a new metasurface design method, which can realize efficient separation and detection of multiple polarization states on a single metasurface, so as to overcome the shortcomings of the prior art. SUMMARY

[0005] The purpose of the present application is to provide a design method and system of a polarization detection metasurface, which aims to solve the problem of how to realize efficient separation and detection of multiple polarization states on a single metasurface.

[0006] In a first aspect, the present application provides a design method of a polarization detection metasurface, comprising:

[0007] establishing a microstructure model of the metasurface, and scanning the phase delay of the microstructure with different geometric sizes under x and y polarizations through a full-wave simulation algorithm;

[0008] specifying two groups of orthogonal polarization states to be separated and their target propagation angles, calculating the supercell size and the number of microstructures contained therein according to the target propagation angles, and confirming the polarization beam splitting target required under the two groups of orthogonal polarization states;

[0009] calculating the Jones matrix of each microstructure in the supercell according to the phase delay, and selecting a group of microstructure parameters as the initial solution for optimization of the metasurface;

[0010] establishing a supercell model according to the initial solution and performing forward propagation simulation to obtain the diffraction order intensity distribution under the two groups of orthogonal polarizations, and constructing a loss function for iterative optimization; and obtaining an optimal supercell structure that meets the polarization beam splitting target.​

[0011] The optimal supercell structure is two-dimensionally periodically expanded to form a complete super surface structure, so as to realize spatial separation and detection of the polarization state of incident light.

[0012] In a second aspect, the embodiments of the present application provide a design system of a polarization detection super surface, which comprises:

[0013] A phase delay acquisition unit is configured to establish a microstructure model of the super surface, scan phase delays of the microstructure with different geometric sizes under different polarizations through a full-wave simulation algorithm, and acquire the phase delays of the microstructure with different geometric sizes under different polarizations. x and y polarizations;

[0014] A microstructure calculation unit is configured to specify two groups of orthogonal polarization states to be separated and target propagation angles of the two groups of orthogonal polarization states, calculate a supercell size and a number of microstructures contained in the supercell according to the target propagation angles, and confirm polarization beam splitting targets required under the two groups of orthogonal polarization states.

[0015] A matrix calculation unit is configured to calculate Jones matrices of the microstructures in the supercell according to the phase delays, and select a group of microstructure parameters as an initial solution for optimization of the super surface.

[0016] A supercell calculation unit is configured to establish a supercell model according to the initial solution and perform forward propagation simulation, obtain diffraction order intensity distributions under the two groups of orthogonal polarizations, and construct a loss function to perform iterative optimization, so as to obtain an optimal supercell structure meeting the polarization beam splitting targets.

[0017] A super surface generation unit is configured to two-dimensionally periodically expand the optimal supercell structure to form a complete super surface structure, so as to realize spatial separation and detection of the polarization state of incident light.

[0018] The embodiments of the present application have the beneficial effect that the function of polarization beam splitting can be integrated in a supercell unit, the geometric parameters and rotation angles of each microstructure are cooperatively controlled through an optimization algorithm, so as to realize efficient separation of multiple polarization states on a single super surface, avoid crosstalk problems in a traditional space division multiplexing mode, and improve spatial resolution. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] figure 1 The flowchart of the design method of the polarization detection super surface provided by the embodiments of the present application is shown.

[0021] figure 2 A polarization detection principle schematic diagram of the metasurface structure provided by the embodiment of the present application is shown in FIG. 1.

[0022] figure 3 A microstructure model schematic diagram provided by the embodiment of the present application is shown in FIG. 2.

[0023] figure 4 A phase delay of the metasurface provided by the embodiment of the present application under polarization and the relationship between the microstructure length and width are shown in FIG. 3. x 、 y l 、 w

[0024] figure 5 A diffraction order intensity distribution schematic diagram required to be met by the supercell provided by the embodiment of the present application is shown in FIG. 4.

[0025] figure 6 An optimal supercell structure schematic diagram after iterative optimization provided by the embodiment of the present application is shown in FIG. 5.

[0026] figure 7 A diffraction order intensity distribution schematic diagram of two groups of orthogonal polarized light after modulation by the optimal supercell structure provided by the embodiment of the present application is shown in FIG. 6.

[0027] figure 8 A schematic block diagram of a design system of the polarization detection metasurface provided by the embodiment of the present application is shown in FIG. 7. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0029] It should be understood that, when used in the present specification and the appended claims, the terms “comprise” and “include” indicate the presence of described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0030] It should also be understood that the terms used in the present specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the present specification and the appended claims, the singular forms “a”, “an” and “the” are intended to include the plural forms, unless the context clearly indicates otherwise.

[0031] ​​​It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0032] Please see figure 1 , figure 1 A schematic flowchart illustrating the design method of the polarization detection metasurface provided in an embodiment of the present invention;

[0033] like figure 1 As shown, the method includes steps S101 to S105.

[0034] S101. Establish a microstructure model of the metasurface and scan the phase delay of microstructures with different geometric dimensions under x and y polarization using a full-wave simulation algorithm.

[0035] In step S101, the metasurface consists of a substrate layer and multiple microstructures. This metasurface is suitable for multiple wavelength bands, including ultraviolet, visible, near-infrared, and mid-infrared. The substrate layer is made of a material that is transparent to the designed wavelength band, and its refractive index must be lower than that of the microstructure material. The thickness of the substrate layer can be flexibly adjusted according to specific needs, and can be arbitrarily selected within the range of 0.3 mm to 3 mm. The multiple microstructures are arranged in an array. By adjusting the type, size, and arrangement of the microstructures, the phase distribution of the metasurface can be changed, and its phase change range is between 0 and 2π. In addition, materials with a refractive index lower than that of the microstructures can be selectively used to fill the gaps between the superlens microstructures to achieve effective protection of the microstructures.

[0036] In step S101, the length and width of each microstructure are scanned using the finite-difference time-domain method, thus obtaining the dimensions of microstructures with different geometric sizes. x and y Phase delay under polarization. Phase delay refers to the phase delay of a microstructure under different polarizations (light). x polarization and y Under polarized illumination, the phase distribution characteristics of the emitted light wavefront vary with geometric dimensions. By using the finite-difference time-domain method for scanning calculations, the quantitative relationship between each microstructure dimension parameter and the phase delay can be accurately obtained, providing fundamental data for the subsequent optimized design of the metasurface phase distribution. This process requires consideration of the substrate material properties and the microstructure array arrangement to ensure that the phase change range covers the complete period from 0 to 2π.

[0037] S102. Specify the two sets of orthogonal polarization states to be separated and their target propagation angles. Calculate the supercell size and the number of microstructures contained within it based on the target propagation angles, and confirm the required polarization beam splitting targets for the two sets of orthogonal polarization states. The supercell, composed of multiple microstructures, is the smallest unit for achieving polarization separation.

[0038] For step S102, specifically includes:

[0039] Designating two groups of orthogonal polarization states to be separated and their target propagation angles, wherein each group of orthogonal polarization states is centrally symmetrically distributed relative to the propagation direction;

[0040] According to the diffraction grating formula d i sin theta i = m lambda Calculate the supercell size d , wherein, wherein i is the information of the supercell in x or y direction, theta is the required propagation angle of a specific polarization in x or y direction, m is the diffraction order, lambda is the wavelength of the incident light;

[0041] According to the formula N i = round ( d i / p i ) to calculate the number of microstructures contained in the supercell, wherein N i is the number of microstructures in x or y direction, p i is the period size of a single microstructure in x or y direction, round denotes rounding to the nearest integer;

[0042] According to the calculated supercell size and the number of microstructures contained therein, the polarization beam splitting target required under the two groups of orthogonal polarization states is confirmed.

[0043] In the specific scheme of this step S102, the diffraction grating formula is introduced to determine the size of the supercell in x or y direction, and then the number of microstructures in this direction is determined by rounding to the nearest integer, thereby ensuring the matching between the physical size of the supercell and the optical function, which is the premise of realizing the polarization beam splitting target.

[0044] S103, according to the phase delay, calculate the Jones matrix of each microstructure in the supercell, and select a group of microstructure parameters as the initial solution of the super surface optimization.

[0045] For step S103, specifically includes:

[0046] According to the phase delay obtained in step S101, the Jones matrix of each position in the supercell is calculated, and the relationship between the Jones matrix and the microstructure phase delay is as follows:

[0047] ;

[0048] Wherein, J represents the Jones matrix; R represents the rotation matrix; theta meta is the rotation angle of the microstructure, i represents the imaginary unit; e iφx and e iφy represents the complex exponential function, and both are used to represent the phase delay; phi x , phi y respectively, x , y the phase delay of the direction, the phase delay is related to the length l and the width w of the microstructure;

[0049] By adjusting the size of the microstructure to control the phase delay of the two directions, a group of microstructure parameters scanned by the full-wave simulation algorithm is selected as the initial solution of the super surface optimization.

[0050] In the specific scheme of this step S103, the Jones matrix is a tool for describing the influence of optical elements on the transmission of polarized light. This step constructs the Jones matrix through the phase delay and rotation angle of the microstructure in the x and y directions, which can reflect the control ability of the super surface on the polarization state. By adjusting the size (length l and width w ) of the microstructure, the phase of the two orthogonal polarization directions can be independently controlled, thereby providing support for realizing the polarization beam splitting function. The selection of the initial solution is based on the scanning results of the full-wave simulation in step S101, which provides a reasonable starting point for the subsequent optimization process.

[0051] S104, according to the initial solution, a supercell model is established and forward propagation simulation is performed, two groups of diffraction order intensity distributions under orthogonal polarization are obtained, and a loss function is constructed for iterative optimization; obtain the optimal supercell structure that meets the polarization beam splitting target.

[0052] For step S104, specifically includes:

[0053] The initial solution of the Jones matrix is corresponded to the length-width and rotation angle of the corresponding microstructure, a corresponding supercell model is established, and vector full-wave forward propagation simulation is performed under periodic boundary conditions to obtain the diffraction order intensity distribution under the corresponding two orthogonal polarizations;

[0054] The diffraction order intensity distribution under the two orthogonal polarizations and the loss function of the target diffraction order are calculated L , and the genetic algorithm or the stochastic gradient descent algorithm is used to iteratively optimize the geometric parameters and rotation angle of the microstructure of the supercell model, to obtain an optimal supercell structure that meets the polarization beam splitting target;

[0055] wherein the loss function L is:

[0056] ;

[0057] wherein I simulation is the (m, n)th diffraction order intensity distribution obtained by simulation under each polarization; i , j I design is the (m, n)th diffraction order intensity distribution designed; i , j i and j are the indices of the diffraction orders; N x and N y are the total number of diffraction orders in the x direction and the y direction, respectively.

[0058] In the specific scheme of this step S104, the specific implementation of the optimization process is provided, including establishing a supercell model based on the Jones matrix, performing forward propagation simulation to obtain the diffraction intensity distribution, and constructing a loss function (such as a mean square error function) to measure the difference between the simulation result and the design target. Through intelligent optimization algorithms such as genetic algorithm or stochastic gradient descent, the geometric parameters and rotation angle of the microstructure are iteratively optimized, and finally the supercell structure that meets the polarization beam splitting requirement is obtained. The advantage of this method is that it can convert the complex multi-parameter optimization problem into a computable optimization target.

[0059] S105, two-dimensional periodic expansion is performed on the optimal supercell structure to form a complete metasurface structure, realizing spatial separation and detection of the polarization state of incident light.

[0060] For step S105, specifically including: taking the optimal supercell as a basic unit, performing translation replication and arrangement processing in a two-dimensional plane to form a complete metasurface structure, so as to realize spatial separation and detection of the polarization state of incident light.​​

[0061] As can be seen from the above, the forward propagation method using the Jones matrix proposed in the application can separate two groups of non-orthogonal polarization states in the spatial propagation direction by using a supercell. Each microstructure in the supercell has a beneficial deflection effect on the separation of the polarization states, thereby avoiding the high crosstalk problem of using a supercell composed of space division multiplexing alone. At the same time, the array structure composed of the scheme is much smaller than the minimum structure required based on the space division multiplexing method, thereby increasing the imaging resolution.

[0062] Based on the design method of the polarization detection metasurface provided in the above embodiment, the working wavelength of the metasurface structure obtained by the application is 600-650 nm, and the metasurface structure can deflect 0° polarization, 90° polarization, 45° polarization and 135° polarization to four different directions in space, respectively, and the effect is as shown in figure 2

[0063] The specific design process of the metasurface structure is as follows:

[0064] First, a microstructure model as shown in figure 3 is established, the material of the substrate layer is silicon dioxide, the material of the microstructure model is titanium dioxide, the thickness of the substrate layer can be arbitrarily selected between 0.3 mm and 3 mm, the period of the microstructure model is 400 nm, and the height of the microstructure model is 800 nm. By using a full-wave simulation algorithm, the long and wide directions of the microstructure with a rotation angle of 0° are scanned, and the phase delay of the microstructure with different geometric sizes under p and h polarization states is obtained, and the result is as shown in theta meta x y Secondly, two groups of orthogonal polarization states and their target propagation angles are determined, and the target propagation angles are respectively set to (10°, 0°), (-10°, 0°), (0°, 10°) and (0°, -10°). According to the calculation, the number of microstructures of the supercell is 9*9, and the target diffraction order distribution is as shown in figure 4

[0065] Finally, according to the target diffraction order and the phase delay of the microstructure, the supercell is optimized according to the loss function figure 5 , and the algorithm used is the stochastic gradient descent algorithm. The optimized result is as shown in

[0066] L figure 6 figure 7 ​​​​​​​As shown, it can be seen that the crosstalk between diffraction orders is extremely low (<3%), and calibration can ensure the accuracy of polarization detection. By arranging the supercells in cycles, a complete metasurface can be constructed to realize polarization detection function.

[0067] The embodiment of the present application also provides a polarization detection metasurface design system for executing any one of the above-mentioned polarization detection metasurface design methods. Specifically, refer to figure 8 , figure 8 is a schematic block diagram of the polarization detection metasurface design system provided by the embodiment of the present application.

[0068] As figure 8 shown, the polarization detection metasurface design system 800 comprises a phase delay acquisition unit 801, a microstructure calculation unit 802, a matrix calculation unit 803, a supercell calculation unit 804 and a metasurface generation unit 805.

[0069] The phase delay acquisition unit 801 is configured to establish a microstructure model of the metasurface, and scan the phase delay of the microstructure with different geometric sizes under x and y polarizations through a full-wave simulation algorithm.

[0070] The microstructure calculation unit 802 is configured to specify two groups of orthogonal polarization states to be separated and target propagation angles thereof, calculate the supercell size and the number of microstructures contained therein according to the target propagation angles, and confirm the polarization beam splitting target required under the two groups of orthogonal polarization states.

[0071] The matrix calculation unit 803 is configured to calculate the Jones matrix of each microstructure in the supercell according to the phase delay, and select a group of microstructure parameters as the initial solution of the metasurface optimization.

[0072] The supercell calculation unit 804 is configured to establish a supercell model according to the initial solution and perform forward propagation simulation, obtain the diffraction order intensity distribution under the two groups of orthogonal polarizations, and construct a loss function for iterative optimization, and obtain the optimal supercell structure meeting the polarization beam splitting target.

[0073] The metasurface generation unit 805 is configured to perform two-dimensional periodic expansion on the optimal supercell structure to form a complete metasurface structure, and realize spatial separation and detection of the incident light polarization state.

[0074] The system can integrate the polarization beam splitting function in a supercell unit, cooperatively control the geometric parameters and rotation angles of each microstructure through an optimization algorithm, thereby realizing efficient separation of multiple polarization states on a single metasurface, avoiding the crosstalk problem in the traditional space division multiplexing mode, and improving the spatial resolution.

[0075] Those skilled in the art can clearly understand the specific working process of the system and the unit described above for the convenience and brevity of description, which can refer to the corresponding process in the foregoing method embodiments, and will not be described here.

[0076] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A design method for a polarization detection metasurface, characterized in that, include: A microstructure model of the metasurface was established, and the phase delay of microstructures with different geometric dimensions under x and y polarization was scanned using a full-wave simulation algorithm. Specify two sets of orthogonal polarization states to be separated and their target propagation angles. Calculate the supercell size and the number of microstructures contained within it based on the target propagation angles, and confirm the required polarization beam splitting targets for the two sets of orthogonal polarization states. Specifically, this includes specifying two sets of orthogonal polarization states to be separated and their target propagation angles, wherein each set of orthogonal polarization states is symmetrically distributed with respect to the propagation direction center; according to the formula... d i sin θ i = mλ Calculating supercell size d , among which, among which i For supercells in x or y Information on direction θ For a specific polarization x or y The required propagation angle for the direction, m It is a diffraction order. λ The wavelength of the incident light; according to the formula N i = round ( d i / p i ) Calculate the number of microstructures contained in a supercell, where, N i for x or y Number of microstructures in the direction p i For a single microstructure in x or y The magnitude of the period in the direction, round This indicates rounding to the nearest integer; based on the calculated supercell size and the number of microstructures it contains, the required polarization beam splitting targets for the two sets of orthogonal polarization states are confirmed; The Jones matrix of each microstructure in the supercell is calculated based on the phase delay, and a set of microstructure parameters is selected as the initial solution for supersurface optimization. Based on the initial solution, a supercell model is established and forward propagation simulation is performed to obtain two sets of diffraction order intensity distributions under orthogonal polarization. After iterative optimization using a loss function, the optimal supercell structure satisfying the polarization beam splitting objective is obtained. Specifically, this includes: mapping the initial solution of the Jones matrix to the length, width, and rotation angle of the corresponding microstructure, establishing the corresponding supercell model, and performing vector full-wave forward propagation simulation under periodic boundaries to obtain the corresponding two sets of diffraction order intensity distributions under orthogonal polarization; calculating the loss function between the diffraction order intensity distributions under the two sets of orthogonal polarization and the target diffraction order; and using a genetic algorithm or stochastic gradient descent algorithm to iteratively optimize the geometric parameters and rotation angle of the microstructure of the supercell model to obtain the optimal supercell structure satisfying the polarization beam splitting objective. The optimal supercell structure is extended in two dimensions to form a complete metasurface structure, enabling spatial separation and detection of the polarization state of incident light.

2. The design method for a polarization detection metasurface according to claim 1, characterized in that, The establishment of the metasurface microstructure model, and the scanning of the phase delay of microstructures with different geometric dimensions under x and y polarization using a full-wave simulation algorithm, includes: A microstructure model of a metasurface is established, wherein the metasurface is composed of a substrate layer and multiple microstructures; By scanning the length and width of each microstructure using the finite-difference time-domain method, microstructures with different geometric dimensions were obtained. x and y Phase delay under polarization.

3. The design method for a polarization detection metasurface according to claim 1, characterized in that, The process of calculating the Jones matrix of each microstructure in the supercell based on the phase delay, and selecting a set of microstructure parameters as the initial solution for supersurface optimization, includes: Calculate the Jones matrix according to the following relationship. J : ； in, R Represents the rotation matrix; θ meta The rotation angle of the microstructure. i Represents the imaginary unit; e iφx and e iφy The complex exponential function is used to represent phase delay; φ x , φ y They are respectively x , y Phase delay in direction, phase delay and the length of microstructure l With width w Related; By adjusting the size of the microstructure to control the phase delay in two directions, a set of microstructure parameters obtained by full-wave simulation algorithm is selected as the initial solution for metasurface optimization.

4. The design method for a polarization detection metasurface according to claim 1, characterized in that, The loss function L for: ； in, I simulation The ( ) obtained from simulations under each polarization i , j ) diffraction order intensity distribution; I design For the designed ( i , j ) diffraction order intensity distribution; i and j Index for diffraction order; N x and N y They are respectively x direction and y The total number of diffraction orders in the direction.

5. The design method for a polarization detection metasurface according to claim 1, characterized in that, The step of extending the optimal supercell structure in two dimensions to form a complete metasurface structure, thereby enabling spatial separation and detection of the polarization state of incident light, includes: The optimal supercell is used as a basic unit and is translated, replicated and arranged on a two-dimensional plane to form a complete metasurface structure, so as to realize the spatial separation and detection of the polarization state of incident light.

6. The design method for a polarization detection metasurface according to claim 2, characterized in that, The substrate is made of silicon dioxide, the microstructure model is made of titanium dioxide, the period of the microstructure model is 400 nm, and the height of the microstructure model is 800 nm.

7. The design method for a polarization detection metasurface according to claim 1, characterized in that, The two sets of orthogonal polarization states and their target propagation angles are (10°, 0°), (-10°, 0°), (0°, 10°), and (0°, -10°), respectively. The supercell contains 9*9 microstructures.

8. A design system for a polarization detection metasurface, characterized in that, include: The phase delay acquisition unit is used to establish the microstructure model of the metasurface and scan the phase delay of microstructures with different geometric dimensions under x and y polarization using a full-wave simulation algorithm. The microstructure calculation unit is used to specify two sets of orthogonal polarization states to be separated and their target propagation angles, calculate the supercell size and the number of microstructures contained therein based on the target propagation angles, and confirm the required polarization beam splitting target under the two sets of orthogonal polarization states; specifically, it includes: specifying two sets of orthogonal polarization states to be separated and their target propagation angles, wherein each set of orthogonal polarization states is symmetrically distributed with respect to the propagation direction center; according to the formula d i sin θ i = mλ Calculating supercell size d , among which, among which i For supercells in x or y Information on direction θ For a specific polarization x or y The required propagation angle for the direction, m It is a diffraction order. λ The wavelength of the incident light; according to the formula N i = round ( d i / p i ) Calculate the number of microstructures contained in a supercell, where, N i for x or y Number of microstructures in the direction p i For a single microstructure in x or y The magnitude of the period in the direction, round This indicates rounding to the nearest integer; based on the calculated supercell size and the number of microstructures it contains, the required polarization beam splitting targets for the two sets of orthogonal polarization states are confirmed; The matrix calculation unit is used to calculate the Jones matrix of each microstructure in the supercell based on the phase delay, and select a set of microstructure parameters as the initial solution for supersurface optimization. A supercell computational unit is used to establish a supercell model based on the initial solution and perform forward propagation simulation to obtain two sets of diffraction order intensity distributions under orthogonal polarization. After constructing a loss function and performing iterative optimization, the optimal supercell structure that satisfies the polarization beam splitting objective is obtained. Specifically, this includes: mapping the initial solution of the Jones matrix to the length, width, and rotation angle of the corresponding microstructure, establishing the corresponding supercell model, and performing vector full-wave forward propagation simulation under periodic boundaries to obtain the corresponding two sets of diffraction order intensity distributions under orthogonal polarization; calculating the loss function between the two sets of diffraction order intensity distributions under orthogonal polarization and the target diffraction order; and using a genetic algorithm or stochastic gradient descent algorithm to iteratively optimize the geometric parameters and rotation angle of the microstructure of the supercell model to obtain the optimal supercell structure that satisfies the polarization beam splitting objective. The metasurface generation unit is used to extend the optimal supercell structure in two dimensions to form a complete metasurface structure, thereby realizing the spatial separation and detection of the polarization state of incident light.

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